Under most circumstances, it has become increasingly obvious that the environmental impact of contamination, in any of its many and varied forms, is simply unacceptable. In some cases, the location and identification of the particular contamination is readily apparent. In others, the location and identification of the contamination can pose a problem. In any event, the necessary objective is to decontaminate the affected area in some way. Unfortunately, with advances in technology, it is not now uncommon for vast areas to be contaminated or polluted by highly dangerous nuclear or toxic materials. Furthermore, the problem of locating contamination is not lessened merely by the fact an extensive area is involved. Indeed, this fact may aggravate the problem.
Various detectors have been proposed for use in determining the nature and concentration level of a contaminant or pollutant. Typically, however, they do not provide direct information on the location of the contamination. Instead, such information is obtained from maps or some other ground-based reference system. Unfortunately, these references can be inaccurate. This is particularly so when the contamination is airborne or waterborne and dispersed throughout a very large area. Moreover, even after an initial clean up has been accomplished, it is possible for there to be residual contamination, and in such cases it may be necessary to retrace paths over an extended area in order to determine the location of any residual contamination. Also, it is possible that the contamination is not just superficial. In such cases it may also be important to be able to bore into the surface of the earth and locate the point of contamination. Again, knowledge of the precise topographical location is important.
An example of an automated system which is designed to continuously link exact survey positions with field monitoring information is the ultrasonic ranging and data system (USRADS) which has been developed by Martin Marietta Energy Systems, Inc. in cooperation with the U.S. Department of Energy. The USRADS system incorporates a series of receivers on the perimeter of the particular site to be characterized and uses the differences in arrival times of ultrasonic pulses from the detector point to determine the exact location of the detector within the site area. This data is transmitted to a nearby microcomputer which calculates and records the position of the detector along with corresponding survey data. Such a system, however, requires ground-to-ground data links and, consequently, is susceptible to interference from ground clutter and obstacles. Further, such a system is somewhat limited in that the peripheral receivers are essentially stationary and must be appropriately positioned for the conduct of the survey. Accordingly, they may not lend themselves to coverage of a very large area wherein there is rugged topography.
The present invention recognizes that a site characterization system can be employed which does not rely solely on ground references for precisely locating the surveyor's exact position within the area at the time a contamination reading is taken. More specifically, the present invention recognizes that a site characterization system using position information from a GPS satellite will allow for mobile operation of a detector within a preselected site.
In light of the above, it is an object of the present invention to provide a site characterization system which gives reasonably accurate topographical information on the location where a contamination reading is taken within the area of a preselected site. Another object of the present invention is to provide a site characterization system which allows for the characterization of contamination and pollution levels over an extended area. Yet another object of the present invention is to provide a site characterization system which can incorporate a mobile base station and a plurality of mobile on-site stations in order to enhance the flexibility of the system in characterizing a particular selected site. Another object of the present invention is to provide a site characterization system which is compatible with various detectors for determining the respective levels of different contaminants. Still another object of the present invention is to provide a site characterization system which provides accurate site characterization within a relatively short period of time. Still another object of the present invention is to provide a site characterization system which allows characterization of the site in situ without having to extract or remove samples from the site for the conduct of laboratory tests. Yet another object of the present invention is to provide a site characterization system which can generate timely and accurate remediation reports based on waste site characterization results and the applicable regulatory requirements. Finally, another object of the present invention is to provide a site characterization system which is easy to use, relatively simple to manufacture and comparatively cost-effective in its employment.